An engineer testing the thermal properties of a newly discovered moon rock heats the .5 kg moon rock to a temperature of 120 °C. He then places it in a thermally sealed container holding 4 kg of water at an initial temperature of 28 °C. When the rock and water come to thermal equilibrium, they each have a temperature of 40 °C. The specific heat of water is 4180 J/kg·°C.